Re: increased vmap_area_lock contentions on "n_tty: Move buffers into n_tty_data"

[Lin Ming]

On Wed, Sep 25, 2013 at 7:30 PM, Peter Hurley <peter@xxxxxxxxxxxxxxxxxx> wrote:
> On 09/25/2013 05:04 AM, Lin Ming wrote:
>>
>> On Wed, Sep 18, 2013 at 8:22 AM, Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
>> wrote:
>> [snip]
>>>
>>>
>>> Looking over vmalloc.c, the critical section footprint of the
>>> vmap_area_lock
>>> could definitely be reduced (even nearly eliminated), but that's a
>>> project
>>> for
>>> another day :)
>>
>>
>> Hi Peter,
>>
>> I also looked over vmallo.c, but didn't find obvious way to reduce the
>> critical section footprint.
>> Could you share some hints how to do this?
>
>
> vmap_area_list is an RCU list.
> get_vmalloc_info() doesn't need to take the vmap_area_lock at all.
> Look at __purge_vmap_area_lazy() for a howto.

Looking at it now ...

Thanks,
Lin Ming

>
> Regards,
> Peter Hurley
>
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